Elucidation of the buildup mechanism of eumelanin particles and specific isolation of intermediates

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Eumelanin is a biological pigment with extraordinary materials properties like radiation protection, radical scavenging, paramagnetism, controlled drug release, and hybrid electrical conductivity. The buildup of melanin pigments includes a molecular and a supramolecular aspect. The molecular aspect is quite well understood. The supramolecular buildup to the final particles however, is mostly unknown. This is to a great extent due to the specific challenges, connected to this system, as the complete synthesis consists of three major, overlapping aspects: Monomer synthesis, polymerization, and supramolecular particle formation. Moreover, each aspect consists of several reaction steps.First results on the particle formation have been gained in own preliminary research. It became clear that the buildup consists of four distinct, hierarchical levels. The specific particle types are quite monodisperse and are distinguishable by size variations of one order of magnitude each. Based on this, a mechanism for the complete buildup process was proposed, which is included in this proposal as working hypothesis.The aim of this project is a complete elucidation of the supramolecular buildup of eumelanin. Additionally, specific isolation of every particle type within this buildup in applicable amounts is aspired. This is realized by a three-fold guiding principle consisting of (i) a tailor-made reactor for parameter control and in situ analytics, (ii) time resolved scattering methods, and (iii) microscopy.First, influences of the various parameters and precursors on the supramolecular buildup will be investigated with this approach, to gain control over the process. This shall allow for acceleration, deceleration, or inhibition of each step within the buildup. Moreover, the underlying mechanisms of each buildup-step will be elucidated completely, to gain a deep understanding of the entire process. The combined results will finally enable stable isolation of gram-amounts of every particle type for future application in innovative materials.